1. Field of the Invention
The invention relates to an accelerometer with an inertial mass suspended in a housing, and an apparatus for the measurement of a force acting on the inertial mass.
2. Description of the Prior Art
The prior art includes accelerometers, such as in German Pat. No. DE-PS 26 24 884, in which, for the measurement of the force, two opposite reflecting surfaces form a gap, whose enclosed angle can be modified by a force acting on the inert mass. As a result of a change in the gap angle, the number of reflections changes, as well as the angle of reflection, measured toward the reflecting surface, of a beam of light emitted from the light source at a determined angle, and thus the intensity of the light which falls into the light inlet opening. Such a measurement is difficult and expensive, and cannot be used without further modification on all parts of the vehicle, since it is susceptible to interference and quite sensitive.
In other accelerometers of the prior art, for example, U.S. Pat. No. 4,104,921, entitled "Piezoelectric Acceleration Transducer", which corresponds to German Laid Open Patent Application No. DE-OS 25 56 298, the inertial mass acts on a piezo-element when an acceleration force occurs. The resulting piezo-electric charge is measured, and is used as a measurement for the acceleration force which is present. In practice, it has been shown that ordinary piezo-ceramics exhibit irregular and uncontrolled behavior as a function of temperature and aging effects. Overall, such piezo-electric accelerometers are very cost-intensive and difficult to use in technological applications.
The prior art also includes pure accelerometers, such as in German Pat. No. DE-PS 26 24 884, in which, for the measurement of the force, two opposite reflecting surfaces form a gap, whose enclosed angle can be modified by a force acting on the inert mass. As a result of a change in the gap angle, the number of reflections changes, as well as the angle of reflection, measured toward the reflecting surface, of a beam of light emitted from the light source at a determined angle, and thus the intensity of the light which falls into the light inlet opening. Such a measurement is difficult and expensive, and cannot be used without further modification on all parts of the vehicle, since it is susceptible to interference and quite sensitive.
Another example of the proir art is U.S. Pat. No. 4,477,732, entitlted "Sensor For Acceleration", which has a first photoconductor disposed in a suspended body. This first photoconductor leads light into the body from an outside light source. The light is then conducted to each of three additional photoconductors when each is aligned with the first photoconductor as the body moves within a housing. At the end of each of the three additional photoconductors there is connected a photo element which converts the light falling thereon to an electrical signal which is connected into an acceleration-related signal.
All of the afore-mentioned patents are incorporated herein by reference as if fully set forth herein in their entirety.